• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.3
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• pp.90-103
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• 1998

The purposes of this study are to estimate the economic value and reasonable entrance fee of the Yeido Park, which is under construction in Seoul, by conduct the face-to-face interview. A total of 645 daults were selected by two stage cluster sampling. The senario was designed to meet the requirements for doubgle-bounded dichotomous choice CVM, and distributed with the photograph to epict and compare the current and suggested conditions. A donation vehicle and entrance fee were utilized to find the possibility of strategic behaviors and protest zero, and to make the data estimatable tfor interval censored survival analysis. Date was calibrated by the survival analysis to eleminate the 'fat-tail problem'. Weibull distribution was assumed as a baseline distrubution. The mean WTP of donation and entrance fee was ￦5,281 and ￦783, respectively. The economic value of this park was determined by aggregating the mean value, giving a total WTP for the population of ￦36,861,645,000. This economic value was composed with the use value and existence value. The calibrationi of the Weibull proportional hazard model showed that nearness to the park, age, intention to isit the park, and educational attainment were significant independent variable to influence an amount of donation.

• Plant Journal
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• v.15 no.2
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• pp.46-55
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• 2019

This paper presents a LNG Liquefaction cycle configuration using two stages of methane expansion (i.e. spliting into two stages as warm & cold to generate an additional inflection point within a cold composite curve) and a single stage of nitrogen expansion to improve the efficiency of the conventional Methane & Nitrogen Expansion Cycle. In comparison with Double Nitrogen Expansion Cycel and Methane & Nitrogen Expansion Cycle, the cycle efficiency has increased approximately from 13.92 and 13.13 to 12.08 kW/ton/day (8~15% efficiency increase). A Life Cycle Cost (LCC) analysis based on Net Present Value (NPV) also show an improvement in therms of project NPV, against a minor increment of a CAPEX.

• Journal of Korean Association for Spatial Structures
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• v.22 no.1
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• pp.17-24
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• 2022

Currently, the construction trend of high-rise structures is changing from a cube-shaped box to a free-form. In the case of free-form structures, it is difficult to predict the behavior of the structure because it induces torsional deformation due to inclined columns and the eccentricity of the structure by the horizontal load. For this reason, it is essential to review the stability by considering the design variables at the design stage. In this paper, the position of the weak vertical member was analyzed by analyzing the behavior of the structure according to the change in the core position of the twisted high-rise structures. In the case of the shear wall, the shear force was found to be high in the order of proximity to the center of gravity of each floor of the structure. In the case of the column, the component force was generated by the axial force of the outermost beam, so the bending moment was concentrated on the inner column with no inclination.

• Journal of ILASS-Korea
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• v.27 no.1
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• pp.11-17
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• 2022

In upcoming Post Stage-V and Tier 5 regulations of construction machineries, nitrogen oxide (NOx) emissions are strictly limited in cold start conditions. In response to this, a method of improving NOx conversion efficiency has been applied by installing an electric heating catalyst (EHC) in front of conventional urea-SCR systems so that the evaporation and thermal decomposition of urea-water solution can be promoted in cold start conditions. In this strategy, the evaporation and thermal decomposition of urea-water solution and corresponding NOx conversion efficiency are governed by temperature conditions inside the EHC. Therefore, characterizing the temperature distribution in the EHC under various operating conditions is crucial for the optimized operation and control of the EHC in Urea-SCR systems. In this study, a 1-D modeling analysis was performed to predict the heater surface temperature distribution in EHC under various operating conditions. The reliability of prediction results was verified by comparing them with measurement results obtained using an infrared (IR) camera. Based on 1-D analysis results, the effects of various EHC operation parameters on the heater surface temperature distribution were analyzed and discussed.

• Computers and Concrete
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• v.30 no.4
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• pp.277-287
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• 2022

Due to the scarcity of extortionate experimental data, fatigue failure of the reinforced concrete (RC) element might be achieved economically adopting nonlinear finite element (FE) analysis as an alternative approach. However, conventional implicit dynamic analysis is expensive, quasi-static method overlooks interaction effects and inertia, direct cyclic analysis computes stabilized responses. Apart from this, explicit dynamic analysis may provide a numerical operating system for factual long-term responses. The study explores the fatigue behavior based on a simplified explicit dynamic solution employing nonlinear time domain analysis. Among fourteen RC beams, one beam is selected to validate under static loading, one under fatigue with the experimental study and other twelve to check the detail fatigue behavior. The SWOT (Strength, Weakness, Opportunities, Threats) analysis has been carried out to pinpoint the detail scenario in the adoption of numerical approach as an alternative to the experimental study. Excellent agreement of FE and experimental results is seen. The 3D nonlinear RC beam model at service fatigue limits is truthful to be used as an expedient contrivance to envisage the precise fatigue behavior. The simplified analysis approach for RC beam under fatigue offers savings in computation to predict responses providing acceptable accuracy rather than the complicated laboratory investigation. At higher frequency, the flexural failure occurs a bit earlier gradually compared to the repeated loading case of lower frequency. The deflection increases by 6%-10% at the end of first cycle for beams with increasing frequency of cyclic loading. However, at the end of fatigue loading, greater deflection occur earlier for higher load range because of more rapid stiffness degradation. For higher frequency, a slight boost in concrete compressive strains at an initial stage of loading has been seen indicating somewhat stepper increment. Stiffness degradation in larger loading cycle at same duration escalates the upsurge of the rate of strain in case of higher frequency.

• Journal of the Korea Institute of Building Construction
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• v.20 no.2
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• pp.147-153
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• 2020

It is important to estimate the optimal construction cost at the early stage of the project. In this regard, conceptual cost estimate is an important factor for estimate optimal construction cost. However, domestic conceptual cost estimate are only used as cost per unit area according to the building type, and it's accuracy is not high. Hence, the purpose of this study is to calculate the approximate quantity and cost for reinforcing bars, concrete, and formwork by presenting a regression formula based on the total floor area of the common work items in the frame work. In order to verify the accuracy and validity of the regression formula presented in this study, a comparative analysis was performed by applying the regression formula and the traditional approximate quantity take-off method to real cases. As a result, the estimated error rate of the traditional method was -102~+55%, and exceeded the estimated conceptual cost estimate accuracy range of -50~+100% suggested by AACE(American Association of Cost Engineering). On the other hand, the error rate of the regression formula method presented in this study was -6.4~+11.62%. This can be used not only for conceptual cost estimate range of accuracy, but also for detailed estimates. However, it is necessary to analyze the factors that affect the unit price as well as quantity in order to calculate the appropriate cost.

• Korean Journal of Construction Engineering and Management
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• v.20 no.5
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• pp.21-30
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• 2019

Environmental and energy issues such as abnormal climate and depletion of fossil fuel due to global warming have emerged as a critical task to threaten human survival. As a result, interest in the Zero Energy Building is increasing as it is an innovative building that can significantly contribute to building energy reduction and greenhouse gas reduction. In the market, however, the added cost of construction is a major stumbling block to the revitalization of the Zero Energy certification. In this study, general private apartment complexes were selected for research, detailed elements for Zero Energy certification were presented based on the construction criteria for eco-friendly houses from the initial design stage, and the cost efficiency analysis of the components for certification were presented. It has been analyzed that only Grade 3 certification can be implemented in apartments due to technical level and physical limitations. Also, after reviewing the cost trend during the lifecycle cost, all expenses can be recovered within 13 years after completion only in the case of grade 5 of the Zero Energy Building. The additional costs proposed in the present study are reflected appropriately in the review of projects for apartments scheduled for order in the future to contribute to the revitalization of the Zero Energy Building certification.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.219-228
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• 2006

In urban areas, tunnelling induced ground deformations, particularly ground settlements should be considered in order to minimize the damage of adjacent structures. Therefore, an appropriate monitoring system for the tunnel construction should be setup at the planning or design stage. A number of studies on ground settlements due to tunnelling in soft ground have been carried out so far. However, most studies have focused on clay soil rather than sand soil. In particular, a few studies on behaviour of subsurface deformations in granular material have been reported. In this study, two-dimensional laboratory model test with aluminium rods regarded as continuum granular material and close range photogrammetric technique, and numerical analysis were carried out in order to identify the behaviour of subsurface deformations due to shallow tunnelling. Direction and magnitude of displacement vectors from the model test was identical to the numerical analysis. In particular, the vector direction was appeared to be toward a point below the tunnel invert level. A narrow 'chimney or tulip like' pattern of vertical displacement was confirmed by both the model test and numerical analysis. This is consistent with the field data. In addition to the qualitative comparison, the quantitative comparison of subsurface settlements according to 2D volume loss showed good agreement between the model test and numerical analysis. Therefore, close range photogrammetric technique applied in the model test may be used to validate the result from the continuum numerical analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.2 no.3
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• pp.25-36
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• 2000

The purpose of this research work is to propose an analytical method of tunnel design based on reasonable site data. Therefore the proposed design method consists of monitoring data and Modified In Situ Rock Model. Also the Rock Mass Rating for very poor quality rock is very difficult to estimate, the balances between the ratings may no longer gives a reliable basis for the rock mass strength. But in reality Rock Mass Rating is only the property which can be obtained from face mapping records of the exposed tunnel face during construction stage. Evaluation of rock parameters for the actual design prior to tunnel construction should be corrected during tunnelling process in particularly complex ground conditions. This study intends to investigate application of in-situ rock model to soft rock tunnelling (weathered rock) by face mapping results and site measurement data that are obtained at the costraction site of Seoul Subway Tunnel. For the preparation of more reliable ground parameters, the Rock Mass Rating values for the weathered rocks were modified and readjusted in accordance with the measurement data. The modified input parameters obtained by the proposed method are used for the prediction of the tunnel behavior at subsequent construction stages. The results of this study revealed that more reasonable feed back tunnel analysis can be possible as suggested. Ample measurement data would be able to confirm the new proposed technique in this research work.

• Korean Journal of Construction Engineering and Management
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• v.18 no.3
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• pp.95-104
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• 2017

Recently, patent information related to building information modeling (BIM) has been increasing owing to BIM adoption within the construction sector. However, only a few research studies have focused on identifying trends in the domestic and foreign BIM technology based on comprehensive and objective data. Therefore, this study aims to analyze technical competitiveness in the global BIM market using patent information. The patent information is compiled from WIPSON and consists of 73 South Korea, 59 USA, 206 China, and 31 Japan applications. Based on patent information, this study objectively observes domestic and foreign technological BIM trends. As a result of the technology entry analysis by the year, starting from physics (G section) to electricity (H section), the performing operations (B section), and the fixed structure (E section) has been expanded gradually. According to the portfolio analysis, the BIM patent is currently in its early stage of development. Through this research, utilizing patents as a basis for future development will be expected to consult with the differentiation of strategy and setting of direction.